Hercules JXD - Page 18

TM
9–1706
HERCULES JXD GASOLINE ENGINE FOR SCOUT CARS 9-10
(
3
)
Steady
needle
,
low
vacuum
. -
If
the
vacuum
is
between
8
and
12
inches
,
the
trouble
might
be
caused
by
loose
valve
guides
,
worn
piston
rings
,
poor
oil
,
or
a
manifold
leak
.
( 4 ) Steady needle , very low vacuum . - If the vacuum should drop
below 5 inches with a steady needle , the trouble is undoubtedly a
manifold leak .
(
5
)
Gradual
drop
.
-
If
a
normal
reading
is
obtained
when
the
engine
starts
and
the
needle
gradually
drops
,
the
trouble
would
probably
be
found
in
the
exhaust
system
-
probably
a
choked
muffler
.
( 6 ) Irregular
drop
, normal
vacuum
. - If the
engine
pulls
a normal
vacuum
but
the
needle
drops
at irregular
intervals
, the
trouble
might
be
caused
by
gummy
valve
stems
, rich
mixture
, lean
mixture
, or
defective
spark
plugs
.
( 7 ) Regular drop , normal vacuum . - A periodic drop or regular
drop with a normal vacuum indicates a chipped valve , a burned
valve , a leaky valve , or a head gasket leak .
( 8 ) Slow movement , low vacuum . - A low vacuum with a slowly
moving needle might indicate late valve timing , poor carburetor
adjustment
,
defective spark plugs
, poor
ignition
, or
gummy valve
stems .
(
9
)
Wide
variations
.
An
oscillating
needle
over
a
wide
range
with
the
variation
increasing
with
increased
speed
indicates
weak
or
broken
valve
springs
.
SECTION
V
CLUTCH
Paragraph
Description
---
10
Troubleshooting
11
Removal
of
assembly
.
12
Disassembly
13
Maintenance
14
Assembly
15
Installation
16
10. Description ( fig . 1 ) .— The clutch assembly is bolted to the
engine flywheel . It is the dry disk , single plate type , incorporating
a
mechanical vibration dampener
and
automatic adjustment
to com
pensate for wear .
a . Construction ( fig . 2 ) .— The flywheel forms a part of the clutch
housing and also acts as the front plate of the clutch . Friction ma
terial is riveted to both sides of the driven plate . Between the rear
lining and disk are six crimped spring steel segments which consti
tute a cushioning effect for smooth operation . A circle of six coil
11